Multiple functionality in a virtual storage area network device

ABSTRACT

In one aspect of the present description, a connection between a predetermined input port and a predetermined output port is created in a partition of a VSAN switch, in which the connection is a destination address independent physical layer connection conforming to the physical layer of a communication protocol. Another connection between a plurality of input ports and a plurality of output ports may be created in another partition of the VSAN switch, in which the connection is a multi-layer connection which includes a network layer connection conforming to the network layer of the communication protocol. Other features and aspects may be realized, depending upon the particular application.

BACKGROUND

1. Field

The present description relates to a method, system, and computerprogram for switching data in a communication fabric in a storage areanetwork.

2. Description of Related Art

A storage area network (SAN) is frequently used to couple remotecomputer storage devices such as disk arrays, tape libraries, opticaljukeboxes or other storage devices, to hosts in a manner which permitsthe storage devices to appear to the operating systems of the hosts aslocally attached to the hosts. Fibre Channel (FC) is a high speednetworking technology in which signals may be transmitted over varioustransmission media including fiber optic cable or twisted pair coppercables, for example.

In a Fibre Channel SAN, devices may be connected together in varioustopologies. For example, in Point-to-Point topology, devices may beconnected directly together. In an Arbitrated Loop topology, devices maybe connected in a loop or ring. In a switched fabric topology, thedevices or loops of devices may be connected through Fibre Channelswitches.

A Fibre Channel switch is a network switch compatible with the FibreChannel protocol. A network switch is a computer networking device thatconnects together segments of a network. A network switch typicallyprocesses and routes data at protocol layers which includes at least thedata link layer (layer 2 of the Open Systems Interconnection (OSI) modelor layer FC1 of the Fibre Channel model, for example). Network switchesthat additionally process data at the network layer (layer 3 of the OSImodel or layer FC2 of the Fibre Channel model, for example) and aboveare often referred to as multilayer switches.

A Fibre Channel switch allows the creation of a Fibre Channel fabricwhich is often a major component of many storage area networks. A FibreChannel fabric typically includes a network of Fibre Channel devices,which allows many-to-many communication. Other features such as devicename lookup, security, and redundancy are also often provided by such anetwork. Fibre Channel switches can implement “zoning” to disableunwanted traffic between certain fabric nodes.

A virtual storage area network (VSAN) is typically a collection of portsfrom a set of connected Fibre Channel switches, that form a virtualfabric. A port in Fibre Channel terminology is generally any entity thatactively communicates over the network, and is not necessarily ahardware port. Such a port is usually implemented in a device such asdisk storage, a device adapter on storage, a host bus adapter (HBA) on aserver or a Fibre Channel switch. Multiple pairs of ports typically maycommunicate simultaneously in a fabric.

The use of VSANs allows traffic to be isolated within specific portionsof the network. Thus, if a problem should occur in one VSAN, thatproblem can often be handled with a minimum of disruption to the rest ofthe network. VSANs usually can be configured separately andindependently, as well.

Ports within a single Fibre Channel switch often can be partitioned intomultiple VSANs, which can share hardware resources including hardwareports. Conversely, multiple switches typically can join a number ofports to form a single VSAN.

A VSAN, like each FC fabric, may offer different high-level protocolssuch as FCP (Fibre Channel Protocol), FCIP (Fibre Channel over InternetProtocol), FICON (Fiber Connection), and iSCSI (Internet Small ComputerSystems Interface or Small Computer Systems Interface over TCP/IP(Transmission Control Protocol/Internet Protocol)), for example. EachVSAN may be a separate self-contained fabric having different featuressuch as distinctive security policies, zones, events, memberships, andname services, for example. Traffic may also be separate in thedifferent VSANs. Unlike a typical fabric that is resizedswitch-by-switch, a VSAN often may be resized port-by-port.

In addition to multi-layer switches such as a VSAN, a fabric may alsoinclude physical layer switches which provide user-configurablededicated communication paths between respective ports. The physicallayer refers to Layer 1 of the OSI or layer FC0 of the Fibre Channelmodel, for example. An example of a physical layer switch is an APCON“Intellapatch” physical switch.

A fabric may also include a debug device which performs trace captureand analysis, for example. Such a debug device is typically inserted atvarious points of the SAN to collect traffic samples. The Finisar “Xgig”device is an example of a debug device for storage area networks.

SUMMARY

In one aspect of the present description, a connection between apredetermined input port and a predetermined output port is created in apartition of a VSAN switch, in which the connection is a destinationaddress independent physical layer connection conforming to the physicallayer of a communication protocol. Another connection between aplurality of input ports and a plurality of output ports may be createdin another partition of the VSAN switch, in which the connection is amulti-layer connection which includes a network layer connectionconforming to the network layer of the communication protocol.

Data may be forwarded through the physical layer connection of the VSANpartition in accordance with the physical layer of the communicationprotocol. In one aspect, data bits of data packets received at thepredetermined input port of the physical layer connection of thepartition, may be forwarded to the predetermined output port of thephysical layer connection of the partition, independently of anydestination address within each data packet.

In another aspect, data may be forwarded through the multi-layerconnection of a partition of the VSAN in accordance with the networklayer of the communication protocol. For example, data packets receivedat one of the input ports of the multi-layer connection of a partition,may be forwarded to one of the output ports of the multi-layerconnection of the partition, as determined by a destination addresswithin each data packet.

In another aspect, the predetermined output port of the physical layerconnection of one partition, and an input port of the multi-layerconnection of another partition, may be a shared port shared by thephysical layer connection of a partition and the multi-layer connectionof a partition. In one result, data bits of data packets forwardedthrough the physical layer connection of a partition, to thepredetermined output port of the physical layer connection of apartition, may be received at the input port of the multi-layerconnection of a partition, which is shared with the predetermined outputport of the physical layer connection of a partition.

In yet another aspect, the predetermined input port of the physicallayer connection of a partition, and an output port of the multi-layerconnection of a partition, may be a shared port shared by the physicallayer connection of a partition and the multi-layer connection of apartition. In one result, data bits of data packets forwarded throughthe physical layer connection of a partition, to the predeterminedoutput port of the physical layer connection of a partition, arereceived from an output port of the multi-layer connection of apartition, which is shared with the predetermined input port of thephysical layer connection of a partition.

In still another aspect, a partition of the VSAN switch may bereconfigured from a physical layer connection conforming to the physicallayer protocol of the communication protocol, to a multi-layerconnection which includes a network layer conforming to the networklayer protocol of the communication protocol.

In another aspect, a partition of the VSAN switch may be reconfiguredfrom a multi-layer connection which includes a network layer conformingto the network layer of the communication protocol, to a physical layerconnection conforming to the physical layer protocol of thecommunication protocol.

In still another aspect, a debug monitor may be created in a VSANpartition to collect and analyze data on the forwarding of data bitsthough the physical layer connection of the partition to detect errors.

In still another aspect, a debug monitor may be created in a VSANpartition to collect and analyze data on the forwarding of data packetsthough the multi-layer connection of the partition to detect errors.

Other features and aspects may be realized, depending upon theparticular application.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a prior storage area network employing apartitionable multi-layer switch and separate, dedicated physical layerswitches and debug devices.

FIG. 2 illustrates an embodiment of a computing environment in which anaspect of the present description may be employed.

FIG. 3 depicts an example of operations for configuring VSAN partitionsand forwarding data through the VSAN partitions in accordance with oneembodiment of the present description.

DETAILED DESCRIPTION

FIG. 1 illustrates one example of a known computing environmentemploying separate, dedicated physical layer switches 20, 21. One ormore hosts 22 communicate Input/Output (I/O) tasks or other processingrequests directed to a storage 24, through a storage area network 26which manages access to the storage 24. In one embodiment, the storagearea network 26 includes a plurality of servers 28 a, 28 b, 28 c, 28 d,each including a processor and a memory. Each processor can include oneor more central processing units (CPUs) available as processingresources to the associated server 28 a-28 d. Although the storage areanetwork 26 is depicted as including four servers 28 a-28 d, for purposesof illustration, it is appreciated that the number of servers may begreater or lesser, depending upon the particular application.

Each server 28 a-28 d may have one or more logical partitions executingin the server 28 a-28 d. Each logical partition separately executes anoperating system and device drivers. The logical partitions comprise adivision of the processors into logically independent but cooperatingprocessing systems each having their own operating systems and devicedrivers. Multiple logical partitions may execute in each server 28 a-28d, managed by a supervisor module for that server 28 a-28 d.

Each device driver provides an interface between the operating system inthe logical partition in which the device driver executes, and a device,such as an I/O adapter including host adapters 32 a, 32 b . . . 32 n,and device adapters 44 a, 44 b . . . 44 n. The host adapters 32 a, 32 b. . . 32 n, enable the servers 28 a-28 d to communicate with the hosts22. The device adapters 44 a, 44 b . . . 44 n enable the servers 28 a-28d to communicate with the storage 24. Thus, the servers 28 a-28 d sharedevices, such as adapters 32 a, 32 b . . . 32 n, 44 a, 44 b . . . 44 n.The variable “n” is used to denote an integer instance of an element,and may indicate different or the same integer value when used withdifferent elements. For instance, 32 n, 44 n, may indicate a same ordifferent number of host adapters 32 n, and device adapters 44 n.

The servers 28 a-28 d communicate with the host adapters 32 a, 32 b . .. 32 n, and the device adapters 44 a, 44 b . . . 44 n, over a fabric 50.The fabric 50 may comprise one or more interfaces providingcommunication paths between the servers 28 a-28 d and adapters. A pathcomprises the hardware in the fabric 50 that enables communication withshared adapters over the fabric. The fabric may comprise for example, aFibre Channel arbitrated loop configuration, a serial loop architectureor a bus interface, such as a Peripheral Component Interconnect (PCI)interface such as a PCI-Express interface. Each server 28 a-28 d may beassigned a portion of the adapters 32 a, 32 b . . . 32 n, 44 a, 44 b . .. 44 n during initialization.

In the example of FIG. 1, the fabric 50 includes a VSAN multi-layerswitch 60 which may be partitioned into a plurality of partitions 1, 2,. . . n, each partition functioning as a virtual multi-layer switch. Themulti-layer switch 60 facilitates sharing of the adapters 32 a, 32 b . .. 32 n, 44 a, 44 b . . . 44 n by each of the servers 28 a-28 d.

The servers 28 a-28 d may be assigned to handle I/O requests directed tospecific volumes configured in the storage 24. The servers 28 a-28 dcommunicate with the storage 24, via the device adapters 44 a, 44 b . .. 44 n over a device network (not shown), which may comprise a localarea network (LAN), storage area network (SAN), bus interface, serialinterface, etc. The servers 28 a-28 d communicate over connections 68enabling processor inter-communication to manage configuring operationsperformed with respect to the shared devices, such as the sharedadapters 32 a, 32 b . . . 32 n, 44 a, 44 b . . . 44 n. In variousexamples, there may be several fabrics connecting adapters 32 a, 32 b .. . 32 n, 44 a, 44 b . . . 44 n.

A storage area network may have multiple servers often referred to as acluster of servers, which receive input/output requests from one or morehosts, to perform input/output operations in which data is read from orwritten to storage through various I/O adapters. Each cluster may haveone or more central processing units (CPUs) in which the processing andmemory resources of the cluster may be apportioned into logicalpartitions, each of which is capable of running an operating system andperforming the functions of a “server”. Thus, as used herein, the term“server” may be used to refer to a physical server or a logicalpartition performing a server function.

A server may have multiple I/O adapters including host and deviceadapters which are accessed through a switch such as the VSAN switch 60.To increase efficiency or availability or both, it is often desirable toshare I/O adapters amongst the servers of the cluster. Thus, a deviceadapter, for example, may be shared as a “virtual” device adapter. Aspreviously mentioned, the servers typically communicate with the deviceadapters and other I/O adapters over the fabric 50 which may compriseone or more interfaces providing communication paths between the serversand adapters.

Each Partition 1, 2 . . . n of the VSAN switch 60 typically includesrouting logic which logically couples a selected upstream port of theswitch 60 to a selected downstream port of the switch 60. In thismanner, a particular server coupled to an upstream port, may belogically coupled to a particular device adapter coupled to a downstreamport, for the purpose of conducting I/O operations between that serverand storage via the device adapter. Similarly, a particular servercoupled to an upstream port, may be logically coupled to a particularhost coupled to a downstream port, for the purpose of conducting I/Ooperations between that server and host via the host adapter. Thus, eachserver may be logically coupled to each I/O adapter of the sharedadapters via the switch.

Each Partition 1, 2 . . . N of the VSAN switch 60 typically furtherincludes error reporting logic. In the course of an I/O operation, anerror may be detected by the Partition 1, 2 . . . N of the VSAN switch60 on one or more of the shared I/O or host adapters. Each Partition 1,2 . . . N of the VSAN switch 60 may be configured or programmed toreport the occurrence of an error to one of the servers.

Various types of errors may occur in an I/O adapter such as a deviceadapter. For example, many communication systems employ a periodiccyclic redundancy check (CRC) to detect alteration of data beingcommunicated. Thus, I/O transactions to a device adapter may have CRCerrors, may be malformed, poisoned, timed out, aborted, unexpected,unsupported, etc. In a fabric, in response to a detected error, detailsof the transaction in which the error arose may be logged in one or moreerror reporting registers. In some applications, a generic error messagemay be sent to a server by the switch 60 via an upstream port.

Hence, each of the servers 28 a, 28 b . . . 28 n may access each of theinitialized I/O adapters via a partition of the switch 60 to conduct I/Ooperations. Conversely, each of the I/O and host adapters may accesseach of the servers to conduct I/O operations such as direct memoryaccess (DMA) operations.

Modern day Storage Area Networks (SANs) as represented by the simplifieddrawing of FIG. 1 frequently become immensely complex, utilizingmultiple components to accomplish important activities. In addition tothe general functionality of a VSAN multi-layer switch, many storagearea networks utilize other devices for controlling, inventorying, anddebugging SANs. These tasks are often done while integrating newcomponents into, or scheduled testing of the existing components of, theSAN.

For example, physical layer switches such as the physical layer switches20, 21 are often utilized to create, modify or disconnect connectionsbetween different components in the SAN 26 without manual, physicalintervention. The functions of the physical layer switches are typicallydedicated and thus limited to the creation, modification anddisconnection of connections.

The SAN 26 may also include a dedicated SAN debug device 70, 72 whichperforms trace capture and analysis. Such a debug device is typicallyinserted at various points of the SAN to collect traffic samples. Forexample, FIG. 1 shows a debug device 70 inserted between the VSANmulti-layer switch 60 and the physical layer switch 21. A second debugdevice may be inserted between the physical layer switch 21 and a deviceadapter 44 n, for example. Some physical layer switches may have a datamonitoring function built in.

FIG. 2 illustrates one example of a computing environment employing anaspect of the present description. Like the computing environmentdepicted in FIG. 1, one or more hosts 22 communicate Input/Output (I/O)tasks or other processing requests directed to a storage 24, through astorage area network 200 which manages access to the storage 24. In oneaspect of the present description, the storage area network 200 includesa fabric 204 having a virtual storage area network (VSAN) switch 210which can reduce or eliminate the need for physical layer switches suchas the physical layer switches 20, 21 employed in the storage areanetwork 26 of FIG. 1.

As explained in greater detail below, selected partitions of the VSANswitch 210 may be configured to provide the functionality of a physicallayer switch, thus obviating use of a separate, dedicated physical layerswitch device such as the physical layer switches 20, 21 (FIG. 1) It isbelieved that prior VSAN switches such as the VSAN switch 60 of FIG. 1typically provide substantially the same functionality to all partitions1, 2 . . . n of the VSAN switch 60. The minimum functionality of eachpartition partitions 1, 2 . . . n of the VSAN switch 60 is believed tobe that of a multi-layer switch which processes data at the networklayer (e.g. FC2 in the FC model, or layer 3 in the OSI model) and above.

In accordance with the present description, the functionality providedto the partitions A, B, C . . . N of the VSAN switch 210 may be alteredsuch that the functionality of one partition differs significantly fromthat of another. For example, the functionality of Partition A of theVSAN switch 210 may be “dumbed down” relative to that of a full functionpartition such as Partition B, for example, which functions as amulti-layer switch. More specifically, the Partition A may be configuredto function as a physical layer switch which provides user-configurable,address-independent communication paths among respective ports 220 a,220 b . . . 220 n and 224 a, 224 b . . . 224 n in accordance with thephysical layer FC0 of the FC model, for example. By comparison,Partition B may be configured to function as a multi-layer switch toprocess data at the network layer (FC2 in the FC model) and above. Thus,by adding a partition to the VSAN switch 210 and configuring the addedpartition as a physical layer switch, a separate, dedicated physicallayer switch device external to the VSAN switch 210 may be eliminated.

In another aspect of the present description, the functionality providedto the partitions A, B, C . . . N of the VSAN switch 210 may be furtheraltered. For example, Partition C of the VSAN switch 210 may beconfigured to function not only as a physical layer switch whichprovides user-configurable, address-independent communication pathsbetween respective ports 220 a, 220 b . . . 220 n and 224 a, 224 b . . .224 n in accordance with the physical layer FC0 in the FC model, butalso provides a debug function to perform trace capture and analysiswithin the Partition C.

As another example, Partition D of the VSAN switch 210 may be configuredto function not only as a multi-layer switch to process data at thenetwork layer (FC2 in the FC model) and above, but also to provide adebug function to perform trace capture and analysis within thePartition D. It is appreciated that other functionalities may beconfigured into one or more of the partitions of the VSAN switch 210,depending upon the particular application.

The servers 28 a-28 d communicate with the host adapters 32 a, 32 b . .. 32 n, and the device adapters 44 a, 44 b . . . 44 n, over the fabric204 which may comprise one or more interfaces providing communicationpaths between the servers 28 a-28 d and adapters. The fabric 204 maycomprise for example, a Fibre Channel arbitrated loop configuration, aserial loop architecture or other devices. Various devices such as a businterface (for example a PCI-E (Peripheral ComponentInterconnect-Express interface) may be used to connect to a fabric suchas the fabric 204. Each server 28 a-28 d may be assigned a portion ofthe adapters 32 a, 32 b . . . 32 n, 44 a, 44 b . . . 44 n duringinitialization.

As previously mentioned, in the embodiment of FIG. 2, the fabric 204includes the VSAN multi-functional switch 210 which may be partitionedinto a plurality of partitions A, B, . . . N, each partition capable offunctioning as a different type of virtual switch. The VSANmulti-functional switch 210 facilitates sharing of the adapters 32 a, 32b . . . 32 n, 44 a, 44 b . . . 44 n by each of the servers 28 a-28 d.

The servers 28 a-28 d may be assigned to handle I/O requests directed tospecific volumes configured in the storage 24. The servers 28 a-28 dcommunicate with the storage 24, via the device adapters 44 a, 44 b . .. 44 n over a device network (not shown), which may comprise a localarea network (LAN), storage area network (SAN), bus interface, serialinterface, etc.

In functioning as a physical layer switch, Partition A of the VSANswitch 210 switches bits of data frames or packets received at one ofthe ports 220 a, 220 b, . . . 220 n, 224 a, 224 b, . . . 224 n, toanother port of the ports 220 a, 220 b, . . . 220 n, 224 a, 224 b, . . .224 n, for transmission to a corresponding destination device ordevices. As a physical layer switch, the Partition A providesuser-configurable address, independent communication paths betweenrespective ports 220 a, 220 b, . . . 220 n, 224 a, 224 b, . . . 224 n(e.g., between an “input port” and one or more “output ports.”)

In the Fibre Channel model, the physical layer (FC0) is directed totransmission media such as cables and connectors and provides forestablishment and termination of a connection to a transmission medium,such as a copper or optical cable for example. It is appreciated that apartition of a multi-layer switch may be configured to function as aphysical layer switch instead of a multi-layer switch in accordance withprotocols other than Fibre Channel. For example, a partition may beconfigured to function as a physical layer switch in accordance withlayer 1, the physical layer of the OSI model. Other protocols havingphysical layers may be implemented as well, depending upon theparticular application.

A Physical Layer of a communication protocol typically defines theelectrical and physical connection specifications such as the layout ofpins, voltages, cable specifications, hubs, repeaters, network adapters,host bus adapters (HBAs used in storage area networks) and more. ThePhysical Layer is typically concerned primarily with the interaction ofa single device with a medium. For example, in a manual patch panel, aphysical wire or cable may be physically connected or disconnected tocontrol access to a medium such as a copper wire or an optical cable. Inan electronic patch panel, electronic switches may be turned on or offto control access to a medium such as a copper wire or an optical cable.Thus, Partition A, for example, may be configured to function as aphysical layer switch which provides a user-configurable electronicpatch panel which provides dedicated communication paths amongrespective ports 220 a, 220 b . . . 220 n and 224 a, 224 b . . . 224 nin accordance with the physical Layer FC0 of the FC model, for example.Such an electronic patch panel may be effectively emulated by forwardingpackets to an assigned output port of the physical layer connection byeffectively ignoring address data embedded in the packets. It isappreciated that such an electronic patch panel function may beeffectively provided utilizing other techniques in a partition of a VSANswitch, depending upon the particular application.

In contrast, the higher level layers of a communication protocol such asthe Data Link and network layers are typically directed to interactionsof multiple devices with a shared medium. Thus, in the example of FIG.2, Partition B may be configured to function as a multi-layer switch toprocess data at the network layer (FC2 in the FC model) and above. Inthis example, the shared medium is the multi-layer connection providedby the Partition B. Multiple devices may transmit data in the form ofpackets or frames over the multi-layer connection of Partition B tomultiple devices. The multi-layer connection of Partition B identifiesthe appropriate output port by examining the destination address dataembedded in the packets or frames being transmitted.

Each multi-layer partition of the VSAN switch 210 may include routinglogic which logically couples a selected upstream port of the switch 210to a selected downstream port of the switch 210, in a manner similar tothe multi-layer partitions of the VSAN switch 60. In this manner, aparticular server coupled to an upstream port, may be logically coupledto a particular device adapter coupled to a downstream port, for thepurpose of conducting I/O operations between that server and storage viathe device adapter. Similarly, a particular server coupled to anupstream port, may be logically coupled to a particular host coupled toa downstream port, for the purpose of conducting I/O operations betweenthat server and host via the host adapter. Thus, each server may belogically coupled to each I/O adapter of the shared adapters via theswitch.

Each physical layer partition of the VSAN switch 210 may includestransistor switches which electrically couples a selected upstream portof the switch 210 to a selected downstream port of the switch 210 in adedicated electrical path which continues until the user reconfiguresthe physical layer switch. Alternatively, such a physical layer switchmay be effectively emulated by forwarding packets to an assigned outputport of the physical layer connection by effectively ignoring anyaddress data embedded in the packets. It is appreciated that such aphysical layer switch function may be provided utilizing othertechniques in a partition of a VSAN switch, depending upon theparticular application.

In this manner, a particular server coupled to an upstream port, may belogically or physically coupled to a particular device adapter coupledto a downstream port, for the purpose of conducting I/O operationsbetween that server and storage via the device adapter. Similarly, aparticular server coupled to an upstream port, may be logically orphysically coupled to a particular host coupled to a downstream port,for the purpose of conducting I/O operations between that server andhost via the host adapter. Thus, each server may be logically coupled toeach I/O adapter of the shared adapters via the switch 210.

Each Partition A, B . . . N of the VSAN switch 210 may also furtherinclude error reporting logic. In the course of an I/O operation, anerror may be detected by the Partition A, B . . . N of the VSAN switch210 on one or more of the shared I/O or host adapters. Each Partition A,B . . . N of the VSAN switch may be configured or programmed to reportthe occurrence of an error to one of the servers.

Hence, each of the servers 28 a, 28 b . . . 28 n may access each of theinitialized I/O adapters via a partition of the switch 210 to conductI/O operations. Conversely, each of the I/O and host adapters may accesseach of the servers via a partition of the switch 210, to conduct I/Ooperations such as direct memory access (DMA) operations.

FIG. 3 depicts one example of operations of a storage area network inaccordance with one embodiment of the present description. In oneoperation, a first connection is created (block 310) in a firstpartition of a VSAN switch wherein the first connection is a multi-layerconnection which includes a network layer connection conforming to thenetwork layer of the communication protocol. In the illustratedembodiment, a user at an external computer may configure the VSAN switch210 (FIG. 2) via a control port to create and configure a plurality ofpartitions including a Partition B as shown. It is appreciated that theVSAN switch 210 may be configured using a variety of techniquesincluding automatic programmed configuration.

During configuration, selected input and output ports of the ports 220a, 220 b . . . 220 n and 224 a, 224 b . . . 224 n are assigned to thevarious partitions including Partition B. The assignments need not beexclusive to the various partitions. Thus, selected input and outputports of the ports 220 a, 220 b . . . 220 n and 224 a, 224 b . . . 224 nmay be shared by the various partitions A, B, . . . N being created.

In the illustrated embodiment, Partition B is configured to function asa multi-layer switch to process data at the network layer (FC2 in the FCmodel) and above. Thus, the Partition B is configured to provide amulti-layer connection which includes a network layer connectionconforming to the network layer FC2 of the FC model.

In another operation, a second connection is created (block 320, FIG. 3)in another partition of the VSAN switch wherein the second connection isa destination address independent physical layer connection conformingto the physical layer of the communication protocol. Here too, selectedinput and output ports of the ports 220 a, 220 b . . . 220 n and 224 a,224 b . . . 224 n are assigned to the various partitions includingPartition A, and the assignments to Partition A need not be exclusive toPartition A. Thus, selected input and output ports of the ports 220 a,220 b . . . 220 n and 224 a, 224 b . . . 224 n assigned to Partition Amay be shared by the various other partitions B, . . . N being created.

In the illustrated embodiment, Partition A is configured to function asa physical layer switch to transmit data at the physical layer (FC0 inthe FC model). Thus, the Partition A is configured to provide a physicallayer connection conforming to the physical layer FC0 of the FC model.

In another operation, the multi-layer connection of the first partitionin accordance with the network layer of the communication protocol,forwards (block 330, FIG. 3) data packets received at one of the inputports of the multi-layer connection of the first partition, to one ofthe output ports of the multi-layer connection of the first partition,as determined by a destination address within each data packet. Forexample, the multi-layer connection of Partition B may include a routingtable associated with each port assigned the Partition B. Each datapacket or frame that arrives at a port of the Partition N can identify adestination location (sometimes referred to as a Destination ID or DID).The routing table can provide one or more possible exit ports assignedthe Partition B for routing the frame to the destination location. Inone embodiment, a protocol implemented on multi-layer switch partitionof the VSAN 210, may determine one or more shortest paths to anydestination in the storage area network 200.

A “frame” is typically a digital data transmission unit or data packetthat includes frame synchronization, i.e. a sequence of bits or symbolsmaking it possible for the receiver to detect the beginning and end ofthe packet in the stream of symbols or bits. In the OSI model, a frameis a data packet on the Layer 2 of the OSI model. Thus in the OSI model,a frame is the unit of transmission in a link layer protocol, andconsists of a link-layer header followed by a packet. If a multi-layerreceiver is connected to the system in the middle of a frametransmission, it may ignore the data until it detects a new framesynchronization sequence.

In contrast, a physical layer connection typically does not recognizeframes and transmits data on a bit level. However, it is appreciatedthat a physical layer connection may be effectively provided by a VSANpartition in accordance with the present description by forwarding thebits of frames through the physical layer in accordance with thephysical layer protocol.

In another operation, data bits of data packets received at thepredetermined input port of the physical layer connection of the secondpartition, forwards (block 340, FIG. 3) to the predetermined output port(or ports) of the physical layer connection of the second partition,independently of any destination address within each data packet. Forexample, once the physical layer connection of Partition A has beencreated, data received at an input port assigned to that physical layerconnection is automatically directed to the corresponding output port(s)assigned to that physical layer connection. In contrast to themulti-layer connection of Partition B, the physical layer connection ofPartition A need not examine the destination address data embedded inthe packets or frames being transmitted to identify the appropriateoutput port, since the data received at an input port assigned to thatphysical layer connection of Partition A is automatically directed tothe corresponding output port(s) assigned to that physical layerconnection.

Moreover, the physical layer connection may be programmed to persistuntil the user subsequently reconfigures the physical layer switch ofPartition A to disconnect the physical layer connection. Thus, once thephysical layer connection of Partition A has been created, data receivedat an input port assigned to that physical layer connection continues tobe automatically directed to the corresponding output port(s) assignedto that physical layer connection until the user subsequentlyreconfigures the physical layer switch of Partition A to disconnect thephysical layer connection. The physical layer switch of Partition A canthus function as an electronic patch panel for reconfiguring networkconnections.

As previously mentioned, selected ports of the VSAN switch may be sharedby selected partitions of the VSAN switch. For example, if thepredetermined output port of the port of the physical layer connectionof Partition A, and an input port of the multi-layer connection of thePartition B, is a shared port shared by the physical layer connection ofPartition A and the multi-layer connection of Partition B, data may berouted first through the physical layer switch of Partition A and thenthrough the multi-layer switch of Partition B. Thus, data bits of datapackets forwarded through the physical layer connection of Partition A,may be forwarded to the predetermined output port of the physical layerconnection of Partition A. At the predetermined output port of thephysical layer connection of Partition A, the data bits are received atthe shared input port of the multi-layer connection Partition B fortransmission as data packets through the multi-layer switch of PartitionB.

Similarly, if the predetermined input port of the port of the physicallayer connection of Partition A is shared with an output port of themulti-layer connection of Partition B, data bits of data packetsreceived from the shared output port of the multi-layer connection ofPartition B may be forwarded as data bits through the physical layerconnection of Partition A.

The input and output ports 220 a, 220 b . . . 220 n and 224 a, 224 b . .. 224 n of the VSAN switch 210 shared by selected partitions of the VSANswitch 210 may be external ports accessible by external devices such asthe device adapters, host adapters, and server. The input and outputports 220 a, 220 b . . . 220 n and 224 a, 224 b . . . 224 n of the VSANswitch 210 shared by selected partitions of the VSAN switch 210 mayfurther include internal ports to facilitate sharing by the partitionsof the VSAN switch.

As set forth above, when Partition A was initially created, it wasconfigured as a physical layer switch. In another aspect, shouldcircumstances change, the Partition A may be reconfigured to anothertype of switch. For example, the partition A may be reconfigured from aphysical layer switch which provides a physical layer connectionconforming to the physical layer protocol of the communication protocol,to a multi-layer switch having a multi-layer connection which includes anetwork layer conforming to the network layer protocol of thecommunication protocol in a manner similar to that of Partition B.

Similarly, when Partition B was initially created, it was configured asa multi-layer switch as discussed above. In another aspect of thepresent description, should circumstances change, the Partition B maysimilarly be reconfigured to another type of switch. For example, thepartition B may be reconfigured from a multi-layer switch having amulti-layer connection which includes a network layer conforming to thenetwork layer of the communication protocol, to a physical layer switchhaving a physical layer connection conforming to the physical layerprotocol of the communication protocol in a manner similar to that ofPartition A when originally configured.

In yet another aspect of the present description, a partition, such asPartition C, for example, may be created and configured (orreconfigured) to perform a “debug” function as well as a physical layerswitch function. Thus, in addition to automatically directing datareceived at an input port assigned to the physical layer connection, tothe corresponding output port(s) assigned to that physical layerconnection, the Partition C can also collect and analyze data on theforwarding of data bits though the physical layer circuit connection ofthe Partition C to detect errors.

In a similar manner, a partition, such as Partition D, for example, maybe created and configured (or reconfigured) to perform a “debug”function as well as a multi-layer switch function. Thus, in addition toforwarding data packets received at one of the input ports of themulti-layer connection of the Partition D, to one of the output ports ofthe multi-layer connection of Partition D, as determined by adestination address within each data packet, the Partition D can alsocollect and analyze data on the forwarding of data packets though themulti-layer connection of the Partition D to detect errors.

A partition such as Partition C, D configured to perform a Debugfunction can replicate traffic passing through a selected connection ofthe switch of the partition and perform analysis on the replicatedtraffic to detect errors or otherwise perform a management function.Also, the replicated traffic may be delivered to a port assigned to thepartition for analysis elsewhere within the storage area network 200 orin processors outside the storage area network. It is appreciated thatother data capture, analysis or captured data delivery functions may beperformed by a debug function configured in a partition in accordancewith the present description.

As partitions are created, the user may be presented with options duringsuch partition creation in a VSAN in accordance with the presentdescription, that would allow the user to include, or exclude, functionsthey require or do not need. For example, one partition could beentirely dedicated to standard multi-layer switch features. Anotherpartition could contain both physical layer switches in accordance withthe relevant physical layer protocol, as well as SAN debugging software.A third partition could provide the user with all functionality,allowing the user to choose what is used when needed. Functionalitycould be applied to a select group of physical ports, or to all ports onthe switch.

In one embodiment, to implement the particular types of switches anddebug functions, particular algorithms may be provided for functionsthat are to be included on the partition. It is believed that suchflexibility may significantly reduce the amount of physical hardwareutilized in a datacenter, and may significantly increase the ease withwhich administrators manage their SANs. For example, switch functionsadded to a partition at creation may in turn be eliminated and thenadded back a feature at a time, step by step, to assist with problemidentification.

It is appreciated that a VSAN switch in accordance with the presentdescription may take a variety of physical forms. For example, the VSANswitch 210 may be embodied in a single chassis device with VSANcapabilities, allowing the user to create multiple partitions on thedevice, dedicated to appropriate functionality.

In another embodiment, the VSAN switch 210 may be embodied in a bladewith VSAN capabilities, which could be inserted in a larger device,allowing the user to create multiple partitions on the blade, dedicatedto appropriate functionality. In yet another embodiment, the VSAN switch210 may be embodied in a single chassis device with VSAN capabilities,but where only one partition can be created, dedicated to appropriatefunctionality.

Additional Embodiment Details

The described operations may be implemented as a method, apparatus orcomputer program product using standard programming and/or engineeringtechniques to produce software, firmware, hardware, or any combinationthereof. Accordingly, aspects of the embodiments may take the form of anentirely hardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore,aspects of the embodiments may take the form of a computer programproduct embodied in one or more computer readable medium(s) havingcomputer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, interconnected storage devices, anarray of storage devices, multiple memory or storage devices or anysuitable combination of the foregoing. In the context of this document,a computer readable storage medium may be any tangible medium that cancontain, or store a program for use by or in connection with aninstruction execution system, apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent invention may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Aspects of the present invention are described below with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

In certain embodiments, the system of FIG. 2 may be implemented as acloud component part in a cloud computing environment. In the cloudcomputing environment, the systems architecture of the hardware andsoftware components involved in the delivery of cloud computing maycomprise a plurality of cloud components communicating with each otherover a network, such as the Internet. For example, in certainembodiments, the system of FIG. 2 may provide clients, and other serversand software and/or hardware components in the networked cloud, withscheduling services.

The terms “an embodiment”, “embodiment”, “embodiments”, “theembodiment”, “the embodiments”, “one or more embodiments”, “someembodiments”, and “one embodiment” mean “one or more (but not all)embodiments of the present invention(s)” unless expressly specifiedotherwise.

The terms “including”, “comprising”, “having” and variations thereofmean “including but not limited to”, unless expressly specifiedotherwise.

The enumerated listing of items does not imply that any or all of theitems are mutually exclusive, unless expressly specified otherwise.

The terms “a”, “an” and “the” mean “one or more”, unless expresslyspecified otherwise.

Devices that are in communication with each other need not be incontinuous communication with each other, unless expressly specifiedotherwise. In addition, devices that are in communication with eachother may communicate directly or indirectly through one or moreintermediaries.

A description of an embodiment with several components in communicationwith each other does not imply that all such components are required. Onthe contrary a variety of optional components are described toillustrate the wide variety of possible embodiments of the presentinvention.

Further, although process steps, method steps, algorithms or the likemay be described in a sequential order, such processes, methods andalgorithms may be configured to work in alternate orders. In otherwords, any sequence or order of steps that may be described does notnecessarily indicate a requirement that the steps be performed in thatorder. The steps of processes described herein may be performed in anyorder practical. Further, some steps may be performed simultaneously.

When a single device or article is described herein, it will be readilyapparent that more than one device/article (whether or not theycooperate) may be used in place of a single device/article. Similarly,where more than one device or article is described herein (whether ornot they cooperate), it will be readily apparent that a singledevice/article may be used in place of the more than one device orarticle or a different number of devices/articles may be used instead ofthe shown number of devices or programs. The functionality and/or thefeatures of a device may be alternatively embodied by one or more otherdevices which are not explicitly described as having suchfunctionality/features. Thus, other embodiments of the present inventionneed not include the device itself.

The illustrated operations of FIG. 3 shows certain events occurring in acertain order. In alternative embodiments, certain operations may beperformed in a different order, modified or removed. Moreover, steps maybe added to the above described logic and still conform to the describedembodiments. Further, operations described herein may occur sequentiallyor certain operations may be processed in parallel. Yet further,operations may be performed by a single processing unit or bydistributed processing units.

The foregoing description of various embodiments of the invention hasbeen presented for the purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform disclosed. Many modifications and variations are possible in lightof the above teaching. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto. The above specification, examples and data provide acomplete description of the manufacture and use of the composition ofthe invention. Since many embodiments of the invention can be madewithout departing from the spirit and scope of the invention, theinvention resides in the claims hereinafter appended.

What is claimed is:
 1. A method for use with a host and storage,comprising: operations by a storage area network (SAN) having acommunication protocol, a cluster of servers, a plurality ofinput/output adapters including a host adapter coupled to the host and aplurality of device adapters coupled to the storage, and a virtualstorage area network (VSAN) switch coupling the servers to theinput/output adapters, the operations including: creating in a firstpartition of the VSAN switch, a first connection between a predeterminedinput port of a plurality of input ports and a predetermined output portof a plurality of output ports of the VSAN switch, wherein the firstconnection is a multi-layer connection which includes a network layerconnection conforming to the network layer of the communicationprotocol; creating in a second partition of the VSAN switch, a secondconnection between a predetermined input port of the plurality of inputports, and a predetermined output port of the plurality of output portsof the VSAN switch, wherein the second connection is a destinationaddress independent physical layer connection conforming to the physicallayer of the communication protocol; forwarding through the multi-layerconnection of the first partition in accordance with the network layerof the communication protocol, data packets received at thepredetermined input port of the multi-layer connection of the firstpartition, to the predetermined output port of the multi-layerconnection of the first partition, as determined by a destinationaddress within each data packet; and forwarding in accordance with thephysical layer of the communication protocol, data bits of data packetsreceived at the predetermined input port of the physical layerconnection of the second partition, to the predetermined output port ofthe physical layer connection of the second partition, independently ofany destination address within each data packet.
 2. The method of claim1 wherein the predetermined output port of the physical layer connectionof the second partition, and an input port of the multi-layer connectionof the first partition, is a shared port shared by the physical layerconnection of the second partition and the multi-layer connection of thefirst partition, so that data bits of data packets forwarded through thephysical layer connection of the second partition, to the predeterminedoutput port of the physical layer connection of the second partition,are received at the input port of the multi-layer connection of thefirst partition, which is shared with the predetermined output port ofthe physical layer connection of the second partition.
 3. The method ofclaim 1 wherein the predetermined input port of the physical layerconnection of the second partition, and an output port of themulti-layer connection of the first partition, is a shared port sharedby the physical layer connection of the second partition and themulti-layer connection of the first partition, so that data bits of datapackets forwarded through the physical layer connection of the secondpartition, to the predetermined output port of the physical layerconnection of the second partition, are received from an output port ofthe multi-layer connection of the first partition, which is shared withthe predetermined input port of the physical layer connection of thesecond partition.
 4. The method of claim 1, wherein the operations ofthe SAN further comprise reconfiguring the second partition of the VSANswitch from a physical layer connection conforming to the physical layerprotocol of the communication protocol, to a multi-layer connectionwhich includes a network layer conforming to the network layer protocolof the communication protocol.
 5. The method of claim 1, wherein theoperations of the SAN further comprise reconfiguring the first partitionof the VSAN switch from a multi-layer connection which includes anetwork layer conforming to the network layer of the communicationprotocol, to a physical layer connection conforming to the physicallayer protocol of the communication protocol.
 6. The method of claim 1,wherein the operations of the SAN further comprise creating in thesecond partition of the VSAN switch, a debug monitor to collect andanalyze data on the forwarding of data bits though the physical layerconnection of the first partition to detect errors.
 7. The method ofclaim 1, wherein the operations of the SAN further comprise creating inthe first partition of the VSAN switch a debug monitor to collect andanalyze data on the forwarding of data packets though the multi-layerconnection of the first partition to detect errors.
 8. A computerprogram product for use with a host and storage, the computer programproduct comprising a computer readable storage medium having computerreadable program code embodied therein that executes to performoperations, the operations being in a storage area network (SAN) havinga communication protocol, a cluster of servers, a plurality ofinput/output adapters including a host adapter coupled to the host and aplurality of device adapters coupled to the storage, and a virtualstorage area network (VSAN) switch coupling the servers to theinput/output adapters, the operations comprising: creating in a firstpartition of the VSAN switch, a first connection between a predeterminedinput port of a plurality of input ports and a predetermined output portof a plurality of output ports of the VSAN switch, wherein the firstconnection is a multi-layer connection which includes a network layerconnection conforming to the network layer of the communicationprotocol; creating in a second partition of the VSAN switch, a secondconnection between a predetermined input port of the plurality of inputports and a predetermined output port of the VSAN switch, wherein thesecond connection is a destination address independent physical layerconnection conforming to the physical layer of the communicationprotocol; forwarding through the multi-layer connection of the firstpartition in accordance with the network layer of the communicationprotocol, data packets received at the predetermined input port of themulti-layer connection of the first partition, to the predeterminedoutput port of the multi-layer connection of the first partition, asdetermined by a destination address within each data packet; andforwarding in accordance with the physical layer of the communicationprotocol, data bits of data packets received at the predetermined inputport of the physical layer connection of the second partition, to thepredetermined output port of the physical layer connection of the secondpartition, independently of any destination address within each datapacket.
 9. The computer program product of claim 8 wherein thepredetermined output port of the physical layer connection of the secondpartition, and an input port of the multi-layer connection of the firstpartition, is a shared port shared by the physical layer connection ofthe second partition and the multi-layer connection of the firstpartition, so that data bits of data packets forwarded through thephysical layer connection of the second partition, to the predeterminedoutput port of the physical layer connection of the second partition,are received at the input port of the multi-layer connection of thefirst partition, which is shared with the predetermined output port ofthe physical layer connection of the second partition.
 10. The computerprogram product of claim 8 wherein the predetermined input port of thephysical layer connection of the second partition, and an output port ofthe multi-layer connection of the first partition, is a shared portshared by the physical layer connection of the second partition and themulti-layer connection of the first partition, so that data bits of datapackets forwarded through the physical layer connection of the secondpartition, to the predetermined output port of the physical layerconnection of the second partition, are received from an output port ofthe multi-layer connection of the first partition, which is shared withthe predetermined input port of the physical layer connection of thesecond partition.
 11. The computer program product of claim 8, whereinthe operations further comprise reconfiguring the second partition ofthe VSAN switch from a physical layer connection conforming to thephysical layer protocol of the communication protocol, to a multi-layerconnection which includes a network layer conforming to the networklayer protocol of the communication protocol.
 12. The computer programproduct of claim 8, wherein the operations further comprisereconfiguring the first partition of the VSAN switch from a multi-layerconnection which includes a network layer conforming to the networklayer of the communication protocol, to a physical layer connectionconforming to the physical layer protocol of the communication protocol.13. The computer program product of claim 8, wherein the operationsfurther comprise creating in the second partition of the VSAN switch, adebug monitor to collect and analyze data on the forwarding of data bitsthough the physical layer connection of the first partition to detecterrors.
 14. The computer program product of claim 8, wherein theoperations further comprise creating in the first partition of the VSANswitch a debug monitor to collect and analyze data on the forwarding ofdata packets though the multi-layer connection of the first partition todetect errors.
 15. A system for use with a host, storage and a storagearea network (SAN) having a communication protocol, comprising: avirtual storage area network (VSAN) switch having a plurality of inputports, a plurality of output ports, a processor and a computer readablestorage medium including code executed by the processor to performoperations, the operations comprising: creating in a first partition ofthe VSAN switch, a first connection between a predetermined input portof the plurality of input ports, and a predetermined output port of theplurality of output ports of the VSAN switch, wherein the firstconnection is a multi-layer connection which includes a network layerconnection conforming to the network layer of the communicationprotocol; creating in a second partition of the VSAN switch, a secondconnection between a predetermined input port and a predetermined outputport of the VSAN switch, wherein the second connection is a destinationaddress independent physical layer connection conforming to the physicallayer of the communication protocol; forwarding through the multi-layerconnection of the first partition in accordance with the network layerof the communication protocol, data packets received at thepredetermined input port of the multi-layer connection of the firstpartition, to the predetermined output port of the multi-layerconnection of the first partition, as determined by a destinationaddress within each data packet; and forwarding in accordance with thephysical layer of the communication protocol, data bits of data packetsreceived at the predetermined input port of the physical layerconnection of the second partition, to the predetermined output port ofthe physical layer connection of the second partition, independently ofany destination address within each data packet.
 16. The system of claim15 wherein the predetermined output port of the physical layerconnection of the second partition, and an input port of the multi-layerconnection of the first partition, is a shared port shared by thephysical layer connection of the second partition and the multi-layerconnection of the first partition, so that data bits of data packetsforwarded through the physical layer connection of the second partition,to the predetermined output port of the physical layer connection of thesecond partition, are received at the input port of the multi-layerconnection of the first partition, which is shared with thepredetermined output port of the physical layer connection of the secondpartition.
 17. The system of claim 15 wherein the predetermined inputport of the physical layer connection of the second partition, and anoutput port of the multi-layer connection of the first partition, is ashared port shared by the physical layer connection of the secondpartition and the multi-layer connection of the first partition, so thatdata bits of data packets forwarded through the physical layerconnection of the second partition, to the predetermined output port ofthe physical layer connection of the second partition, are received froman output port of the multi-layer connection of the first partition,which is shared with the predetermined input port of the physical layerconnection of the second partition.
 18. The system of claim 15, whereinthe operations further comprise reconfiguring the second partition ofthe VSAN switch from a physical layer connection conforming to thephysical layer protocol of the communication protocol, to a multi-layerconnection which includes a network layer conforming to the networklayer protocol of the communication protocol.
 19. The system of claim15, wherein the operations further comprise reconfiguring the firstpartition of the VSAN switch from a multi-layer connection whichincludes a network layer conforming to the network layer of thecommunication protocol, to a physical layer connection conforming to thephysical layer protocol of the communication protocol.
 20. The system ofclaim 15, wherein the operations further comprise creating in the secondpartition of the VSAN switch, a debug monitor to collect and analyzedata on the forwarding of data bits though the physical layer connectionof the first partition to detect errors.
 21. The system of claim 15,wherein the operations further comprise creating in the first partitionof the VSAN switch a debug monitor to collect and analyze data on theforwarding of data packets though the multi-layer connection of thefirst partition to detect errors.